Hi R-Users, 
I have plotted a region whose polygon coordinates are given in shp format  ED50 UTM (zone=30) ) using  "readShapePoly" in library(maptools).

Now I need to plot a set of points in that region (my.dataframe, with X and Y geographic coordinates), which have been read using GPS in Longitud-Latitud form (using WGS84 system), so I first need to convert these Longitud-Latitud data into UTM data. To do so, I use package PBSmapping:

attr(my.dataframe,  "projection") <-"LL"
attr(my.dataframe, "zone") <- 30
my.dataframe<-as.PolySet(my.dataframe)
my.dataframeUL<-convUL(my.dataframe)

obtaining the UTM coordinates. But when I plot them in the polygon region, points seem to be badly located. 
I suspect it is due to the ED50 UTM of the polygon versus WGS84 coordenates of the points. If this is the problem, is there a way to convert them into the same format? It it is not the problem, what am I doing wrong?

Thanks a lot in advance. 
Berta. 

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